Creating eyeballs is time consuming! Having to create a new one for every characters so they don't all look the same is even more time consuming! Even more so to have each eyes a bit different! The easy solution to that is to use procedural.
This setup works great in both Eevee & Cylces (most likely with other renderers as well) and is very flexible. The displacement only works in Cycles, its a bump in Eevee. So much more realistic in Cycles or other non real-time renderer, but still very realistic in Eevee!
This file only contains the eyeball and not the skin and it only works in blender! This file isn't intended for game engine uses (Such as Unity & Unreal Engine, etc...) unless you find a good way to bake it all to texture!
The node groups in the materials are clearly labeled for ease of use and the inner workings of the nodes are also super clean and framed with titles so you can understand better what does what!
This file is also the result of a course study that I am currently working on!
Please consider joining my Patreon for only 5$/mo, you'll have access to early releases of my course files and videos!
The eyeball model, Iris model and pupil model (not the skin/eyelids) with the procedural materials ready to use!